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C4

C4 - Malfunction of liquid pipe thermistor for heat exchanger (Indoor Unit)

Daikin · Simple Self Diagnosis by Malfunction Code | Daikin

What does C4 mean?

This code signifies a problem with the temperature sensor (thermistor) on the liquid pipe of the indoor unit's heat exchanger.

Common Causes

  • Faulty liquid pipe thermistor
  • Loose or damaged wiring to the thermistor
  • Incorrect installation of the thermistor

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off power to the unit.

  2. 2

    Visually inspect the wiring connected to the liquid pipe thermistor.

  3. 3

    Turn the power back on.

  4. 4

    If the error code remains, contact a service professional.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

6-06-0 - External protection device activated (Heat reclaim ventilator)6-16-1 - Malfunction of PCB (Heat reclaim ventilator)6-26-2 - Ozone density abnormal (Heat reclaim ventilator)
Source: Simple Self Diagnosis by Malfunction Code | Daikin
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